In-Stat said the rate of downloads has increased as the market for apps has become flooded. Apple's three-year-old App Store, for instance, now offers more than 425,000 apps while Android Market offers more than 200,000.

Philip Schiller, head of Apple product marketing, has said that Apple alone has paid out some $2.5 billion to app developers over the last three years.

The developers receive 70% of the purchase price of their apps sold on the Apple site. Apple's revenue from the site was $1.1 billion through the period, meaning that the App Store has generated some $3.6 billion in overall revenue through mid-2011.

"Largely spurred by the launch of the iPhone, mobile applications have been a strong growth market over the past several years," said Amy Cravens, an In-Stat analyst. "The number of apps available has exploded, which has sparked an increasing rate of downloads."

She said the challenge for developers and app stores will be to compete across multiple mobile platforms.

In-Stat added that the explosive growth of app downloads will keep pressure on them to keep prices low, or even to offer free products. Users now pay an average of $2.50 for a mobile app, the research firm reported.

In-Stat said the spread of smartphones is also boosting app downloads. Smartphones made up one-fourth of all cellular phone shipments in 2010. That number is projected to jump to 45% in 2015, the company said.

Nearly half of all app downloads are now done over Wi-Fi, In-Stat said.